Patent US2273304A successfully refreshed from Google Patents.
Patent US4148660A successfully refreshed from Google Patents.
US4148660A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Plaster molding composition
Assignee: Pmcma Research Group
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Filing: 1977-12-19
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Granted: 1979-04-10
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Expires: 1997-12-19
Abstract
Abstract A fiber-free plaster molding composition which comprises by weight approximately 50-70% gypsum plaster, 5-25% fine expanded perlite, and 5-30% of a non-fibrous filler such as mica, silica, fly ash, pyrophyllite or mixtures thereof. The composition of this invention has good dry blending properties, slurry characteristics, and wet and dry mold features, making it a suitable replacement for fiber-containing molding compositions for low fusion metal casting molds.
Inventors
- 👤 David R. Lankard
- 👤 Walter A. Hedden
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 16:37
CPC Classifications
B; B22; B22C; B22C1/00; Y; Y10; Y10S; Y10S106/00; Y10S106/01; Y10S106/02
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
98 words
In a metal castings molding composition having as its principal component gypsum plaster present in the range of 50-70% by weight of said composition, the improvement comprising the addition of 5-25% by weight fine expanded perlite at least 50% of which will pass through a -50 mesh screen, and the remainder consisting essentially of at least 5% by weight non-fibrous filler selected from the group consisting of mica, silica, fly ash, pyrophyllite, and mixtures thereof, whereby there is produced a fiber-free metal castings molding composition having good dry blend properties, slurry characteristics, and wet and dry mold features.
Claim 2
Dependent Claim
98 words
In a metal castings molding composition having as its principal component gypsum plaster present in the range of 50-70% by weight of said composition, the improvement comprising the addition of 5-25% by weight fine expanded perlite at least 50% of which will pass through a -50 mesh screen, and the remainder consisting essentially of at least 5% by weight non-fibrous filler selected from the group consisting of mica, silica, fly ash, pyrophyllite, and mixtures thereof, whereby there is produced a fiber-free metal castings molding composition having good dry blend properties, slurry characteristics, and wet and dry mold features.
Claim 3
Dependent Claim
26 words
A fiber-free molding composition as set forth in claim 1 wherein said expanded perlite is present in the amount of approximately 10% to 15% by weight.
Claim 4
Dependent Claim
21 words
A fiber-free molding composition as set forth in claim 2 wherein said filler is present in the amount of approximately 25-30%.
Claim 5
Dependent Claim
38 words
A fiber-free molding composition as set forth in claim 3 wherein said filler is a mixture of fine mica and other non-fibrous materials, said fine mica being present in the amount of approximately 5-20% of the total composition.
Claim 6
Dependent Claim
29 words
A fiber-free molding composition as set forth in claim 4 wherein said fine expanded perlite is a mineral at least 85% of which will pass a -325 mesh screen.
Claim 7
Dependent Claim
24 words
A fiber-free molding composition as set forth in claim 3 further including a Terra Alba accelerator at approximately 1% by weight of said plaster.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-04-09 | 1982-10-09 | 1983-04-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-04-09 | 1986-10-09 | 1987-04-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-04-09 | 1990-10-09 | 1991-04-10 | $7700.00 | Window Closed / Lapsed |